**Core Concept**
The development of muscles in the human body is primarily governed by the process of embryonic mesoderm differentiation. Mesoderm is one of the three primary germ layers that form during embryogenesis, giving rise to various tissues, including muscles. The mesoderm differentiates into somatic and splanchnic mesoderm, which further develop into skeletal, smooth, and cardiac muscles.

**Why the Correct Answer is Right**
The correct answer is a muscle that does not originate from the mesoderm. In the human body, muscles can be broadly classified into three types: skeletal, smooth, and cardiac. Skeletal muscles, smooth muscles, and cardiac muscles are all derived from the mesoderm. However, one type of muscle is an exception - muscle derived from the ectoderm, specifically the neuroectoderm. The **skeletal muscles** primarily originate from the somatic mesoderm, while the **smooth muscles** and **cardiac muscles** originate from the splanchnic mesoderm. The **muscle derived from the ectoderm** is the **muscle of the iris**, which is a smooth muscle that controls the size of the pupil.

**Why Each Wrong Option is Incorrect**
**Option A:** The skeletal muscle is a derivative of mesoderm. It arises from the somatic mesoderm.
**Option B:** The smooth muscle is a derivative of mesoderm. It arises from the splanchnic mesoderm.
**Option C:** The cardiac muscle is a derivative of mesoderm. It arises from the splanchnic mesoderm.

**Clinical Pearl / High-Yield Fact**
The development of muscles in the human body is a complex process, and understanding the embryonic origins of muscles is crucial for diagnosing and managing various muscular disorders.

**Correct Answer:** D. Muscle of the iris.